Frequency Analysis
by thinkatory
Summary: Bletchley Park, 1943. Roxy's a programmer on Colossus. Terezi's cracking an Enigma. There's a war on and everyone needs all the distractions they can get.


Historical AU, set during WWII on the Enigma project at Bletchley Park. Roxy/Terezi.

* * *

Here's how it started:

The war broke out. You weren't all "yes, thank you, Nazis, from saving me from tedium and marrying someone and never doing anything again!" but at least you got to work in a factory for real pay and quit your job being a secretary on a typewriter while the men got to do the actual research that you would be so much better at.

Then your best friend Dirk told you that he was going to go across the Atlantic to be a codebreaker, at which point you reminded him you were so much better at it than he was, and he told you to prove it.

So you applied for it, got in, and did.

That's not the important part, so you figure you might as well get it over with. That was before. This is now.

* * *

 _Now_

You got to Bletchley Park after the construction of Colossus, and fell in love with it instantly. Even if a bunch of other people work with it, you take its failures and successes really personally, to the point that all of the Brits kind of think you're silly. But you can't be anyone but you, can you?

About the Wrens! They're very patriotic and welcoming, mostly, and the other codebreakers are hit or miss. Dirk doesn't bother really associating with anyone, but you can't get over being surrounded by people so motivated and interested in all the stuff that you are.

"This is so great. All of it, the whole place. D'you even notice? All you do is... work and read. Come on," you press Dirk affectionately, and poke his arm as he thoroughly enjoys his café lunch (you've already eaten your entire lunch, because deliciousness). "England! I love it here. I'm never going home."

"What about after the war?" he asks.

The ever reasonable Mr. Strider. "What about it?" you answer right back.

"There won't be a job like this for you after the war."

"There will be if I do a really, really good job, and you know it."

"Maybe," Dirk says, and looks up at you through his tinted glasses. "But I doubt it."

"Stop ruining this for me," you say, not entirely serious, and poke his arm again. "Are you going to stay?"

"No. I have to go home." He smiles, nearly, for just a second, and prods you right back in your arm. "This isn't our home. Even if we like it here."

You lower your voice. "You want to go back for him, don't you?"

Dirk says nothing, doesn't look at you, and just eats his sandwich like you're talking about nylons and lipstick and other things that don't concern him. After he finishes chewing and decides to acknowledge you looking at him pointedly, he looks up at you. "I have to go home. Like I said."

"Mmhmm," you say, knowingly, and lean back. "The fashion here is so lovely, I just don't think I'll want to. I mean, I'll miss Jane, I will! But she's so busy, and has the money to come and visit whenever she wants, right?"

"Roxy," Dirk starts.

You sigh, mock-impatiently. "Oh, let a girl dream!"

"You dream all of the time," he says. "I'm surprised you get anything done."

"You dream too." You lean across the table and tilt the brim of his hat up to kiss both cheeks quickly. "Our break is over. Finish your sandwich."

"It's not over. We have ten minutes or so and we're walking distance."

You bounce on your seat. "But I want to get back to work. We're gonna help sock it to them and I can't wait."

He's almost smiling again. You grin. "You're meant to be here," he says. "I hope you can do this forever."

"Good, because I'm going to," you say. "Come on, come on, come on!" You tug on his arm.

"I'm bringing the sandwich," he says patiently, and pulls your hand off of his sleeve. He wraps it up with a napkin, and tosses a fiver down on the table.

"What, no tip?" You prod him again. "Leave a tip."

He glances at you. "You leave a tip."

"I thought you were a gentleman!"

"You wanted equality, here it is."

You snort, and reach into your purse to put a few quid on the table. "All right, wiseguy, let's go."

When you get there, there's a group of trolls huddled together in serious conversation with the lead project heads. You squint and lean on Dirk's shoulder to get a better view. "Who's that? Anyone new? Look, I am not ready to go. I am way too good at this."

Dirk shakes his head at you. "No one new there, though I know we don't see them much. That's the Enigma group." He gently puts you back down on your feet. "Back to work."

"Oh, the actual codebreakers. How much can you do without actual math, though?" you wonder, but go ahead with him.

"Not everything is Colossus. Just because you have a hammer doesn't make everything a nail."

"But I could do the probability math – "

" _It's not about math._ "

"Everything's about math!"

Dirk gives you a nudge, and indicates the Wrens giving you sideways glances. You smack a hand over your mouth and hurry to your station.

There's always time to investigate that later.

* * *

After you're done with work, you take the wrong turn to get your things and accidentally wind up turning a very wrong doorknob.

There's a very awkward pause as what is apparently a heated argument stops dead at your presence. Then you chirp, "Ummm, sorry!" and flee.

You don't even hear anything that's said after you go, probably laughter and cleared throats and maybe brief mockery after calling you a Wren. You just grab your jacket and purse, pull it all together, and practically run out of the door when you don't find Dirk in the building.

He's not at the Tube station either. You sulk quietly as you wait, awkwardly making a point of not awkwardly starting conversations with strangers out of pure nervousness and good intentions, as you've learned that the Brits aren't really that great about that, and then you hear a tapping and raise your head.

You tilt your hat up. You recognize that tapping, and the woman doing it. She'd been blocked in the gaggle of trolls earlier, but the second in command of the Enigma team is impossible to mistake for anyone else, the only smooth broad with red-tinted glasses and a cane she uses to get by without her sight.

What was her name again?

 _Right_ , you're not going to start conversation with her because the Brits already think you're kind of over the top anyway and you want to be friends with people, not be that weirdo who _can't shut up or leave anyone alone_.

 _Tap, tap, tap._ She gets closer to you. Then she stops, nearby you.

"I wanted to thank you for interrupting," she says; you were not expecting her to be Scottish, is your first thought. (What were you expecting?) Then you look around for someone else she could be talking to. Everyone else is studiously ignoring the two of you. She goes on. "Things got heated. I decided to leave. I needed to leave. Sollux can be kind of an arse."

You look around again. Then you say, "You… recognized me?"

She grins. Her grin is terrifying, which is not a bad thing. "Confusing, isn't it?"

You think this may be mockery, because trolls are known for this kind of thing, but you're going to give her the benefit of the doubt. "Yes," you agree, and think quickly. "Smell? I know trolls have a better sense of smell. Not that better than a human is saying much! Oh um I'm actually sorry for interrupting even if it gave you an out, because I guess I can't tell doors apart. Why do you guys even meet in the room next to the coatroom anyway? Doesn't that seem like a really terrible idea to you? Because you're talking about really serious things in there."

"Because it's somewhere to meet, and we trust our people. After screening, of course." She tilts her head up at you, and her mouth opens slightly; is she considering you somehow? Trying to read your facial expression? What is your facial expression, even? You touch your face to check or something, patting it for evidence pointlessly. "You work on Colossus?" she asks, while you're being an idiot.

You stop the face-patting. "Yeah, I mean, yes." What are you saying? Your brain is full of question marks. "Sorry, I'm Roxy Lalonde! I have a degree in mathematics, really haven't had a chance to use it, you know, I hate the circumstances but it's been wonderful working on – I used to do cryptography for fun – "

"I'm Terezi Pyrope," she interrupts you. "I know humans are a little backwards about some things. I don't have any degrees, personally. Natural talents."

"Oh, I'm a natural talent, too. Humans are just stupid, I had to have a degree or no one will take me seriously, which they don't anyway because I'm a woman and that's – oh god, never mind that – " Now you're just rambling nervously, because she's just looking at you with a faint smirk.

"Aren't you going to ask me what the argument was about?" she prompts you.

You stare at her. There's dead silence between you, and she rolls her cane between her fingers. "Above my paygrade?" you try.

She shakes her head at you. "Come on, Lalonde," she says. "You have to at least try."

The train pulls up, then, and she turns her head just slightly and heads towards it.

Oh. Right. You stand there dumbly.

"Are you coming?" Terezi calls.

You nod, then call, "Um, yes!" after her, and run to the train.

* * *

So after Terezi's thoroughly, but not unkindly, shamed you out of your nerves, she actually starts talking, even though you're not sure why.

"They can only do so much. I mean, humans. You're clever and all but your brains don't work like ours. Of course not." She scoffs, then pauses. "No offense. But I still can't really understand what it's like to not have psionics and all the others in the mix."

"Well, we have you," you point out. "Not that you have psionics, but trolls, I mean."

"If you can get a psionic to help you, yeah," she says. "You're lucky we like you."

"We share a planet. And there's a war. I'd hope you'd help." You push your hair behind your ears as she turns to take you in, with… smell? Taste? That puts an inappropriate image in your head you really can't afford to have. "Um… but it's great that you do!"

"The next question you should ask is 'do you have any psychic abilities, Terezi'," she adds.

"You got a script? You should write radio plays or something." You smile to take the edge off of it. "You have any abilities, Terezi?"

She's been waiting to talk about this, natch. Maybe to brag. You think you've got the measure of her. Why she's talking to you, you have no clue. Maybe she's lonely. Maybe she's too tense. Dirk says the others – she's still not talking. "Terezi?" you try.

"Do you feel that?" She looks distant, like she's hearing something.

"No," you say carefully.

"Must be – " Terezi snaps out of it, looking embarrassed and harried. "Right anyway, that's it. I'm a cryptographer, I put things in my head and then all at once they'll sort of, bam, make sense. Except it's not patterns so much as… knowing."

"We could use more trolls like that." You can only imagine how helpful that'd be, figuring out as the code shifts, what the patterns are, or at least if X corresponds to Y or Z. "Or humans. I'm no help that way."

"You said you did cryptography," she reminds you.

"I said I did it for fun, I can't do it to win a war. I'm here to keep - _him_ up and running." You've all had to come up with a way to talk about this in public, after all. (There's a lot of arguments over whether Colossus should be referred to as male or female, and you think, with how much work you and the other Wrens have put into him while he just sits there, that he's _clearly_ a man.)

She looks distant, still, so you clear your throat. "I like him a lot, you know."

"Who, _him_?" Terezi laughs. You like hearing that. "Yeah, I wish I could spend more time there."

"So since I can ask you any questions I want," you start saying, but she raises a hand.

"Just about any," she warns you.

"Tell me more about the 'knowing' thing." You rummage through your purse, and pull out your wallet. "I'll buy, you talk? Can't tell me you're not hungry."

You'll never know if a troll smile looks like a smirk just because of the teeth or not. But that's not to say you don't like it anyway.

* * *

You end up in a chip shop not far from your rented flat with Dirk, and Terezi sits in a booth while you wait for the food. This whole thing is incredibly surreal, and by now you're just wondering if she tracked you and found you and charmed you and now has plans for you, somehow, but that's the thing about the "charmed" part. You're not sure you'd be against any plans. She's charismatic that way.

You bring the food over once it's ready, and consider her where she's lounged. Then she reaches over and grabs her sopor, popping it open with a claw. "I've been on this team for aaaages," she drawls, taking a sip from the bottle.

You look at your own beer. You wonder if this is a good idea, but she starts talking again.

"They gave me applications and told me to look to see if I could pattern out any people who would work. You and the other kid, the one with the glasses sort of like mine? I picked you both."

All you can do is blink, too surprised to react for at least ten seconds. "You picked me?" you repeat.

"Look, I'm not saying you're important, I'm not saying you're not," she explains, "I'm saying you would _work_ , and I don't mean just pecking away like the Wrens – who are great and important in their way – but the, um, what we're up against, Lalonde, it's… pervasive, that's the only word. Hard to see through sometimes."

The Nazis. You don't like talking about them out loud outside of the Park either. The way she says it, though, puts a hollow in your stomach. "Yeah," you say. "Yeah, no, I know."

"Everything we've got we've got to put into it," she says, tone quiet and even. "Every bit of it."

"No, I know." You don't know how much of this you can stand. "Um, Miss Pyrope."

"Terezi," she insists. "Call me Terezi. What?"

"I think we can do it. We've done so much already. There's no point in losing hope because that's all we've got, isn't it, and, I know I sound ridiculous but we're allies, aren't we? And allies help each other, they fight, but they also support each other."

There's a pause; Terezi sips her sopor, and you have a chance to consider what you actually just said, how you sound like a total knucklehead, but how completely true it is and that you don't care because of that. "That's sort of what I said," she says, "but you said it in a much more inspirational, American way, and I have to give you some credit for that."

You open your beer at this point, because it's fine, it's fine, Dirk can't have a problem if you have one beer. "You'll actually give me credit for being American?" you tease her.

She grins in that way again. "I could disapprove, but would you even notice? _Yanks_."

" _Scots_ ," you answer, in your best/worst attempt at an accent, and down more of the beer.

Terezi cringes. "Never do that again," she warns.

"Or what?"

Her eyebrows lift. "I outrank you, you know."

For one second, you're actually concerned, then you remember where you are and how this day has gone. "But you let me buy you fish and chips! I think we're beyond rank."

She concedes the point with a nod. "All right, Lalonde. Just… really, don't."

You shake your head, amused, even if she can't see it. You pause. "Why are you talking to me?" you ask, before you can reconsider.

"It felt right," she answers immediately. "Things happen the way they're supposed to happen, or they should. Sometimes I can feel that."

"Feel what?" you prompt.

"Feel what's right." She picks at her own food, apparently not as hungry as you thought. "When you showed up, it felt right. I mean," she starts again, hurried, "I felt something clicking into place. That's how it feels."

You are now blushing. Your beer bottle is empty, and… maybe you shouldn't have downed that beer so fast. When was the last time you drank, anyway? A few weeks ago? Did you dry out? You always did like hooch better than beer, beer messes with you differently. Why are you thinking about this when – well, better this than the other thing. "I hope that means I'll be helpful," you say, half-questioning.

"Probably," Terezi says thickly, swallowing another bite. "Thanks for buying, by the way."

"Well maybe that's why this felt right, because you were hungry and wanted to unwind with sopor," you say brightly. "I'm keen on a good time, you know."

"Are you?" she says, and you look up in surprise, because you know that tone. Then she pulls out a coin and flips it casually in your direction. You look at it. _Scratch._ "Heads I win, scratch you lose. Means I buy you the next drink."

No, this isn't happening. You're not sure you can – but – there's – there's a war on. And you miss Jake and Jane, and you deserve a break, and Terezi is the best kind of distraction right now, even if she probably outranks you a lot. She outranks you a lot. That should scare you more than this.

"Lalonde," she repeats, and you snap out of it.

"Um," you say, "yeah! Excuse me, sorry, do you want more... something?"

"No," Terezi says easily. "I'll get your beer. You'd be surprised how fast this helps me get through a crowd." She grabs her cane.

"I don't think I would," you say honestly.

"For some reason everyone thinks it's a problem," she says blithely, and gets up. "Just a mo."

You watch her go, a little dazed. You make a decision, in a split second. It feels right to her, it feels right to you. There's a reason for that, patterns or... meant to be? Is that what she meant? Did she mean setting up a possible future? Obviously you're going to have to ask her when she gets back.

You're thinking more clearly after a drink. Dirk can be kind of an unnecessary force for temperance with you, like your grandma or something, and you don't know how you'd even be dealing with this weird situation without a more casual setting anyway. You get so mouthy and awkward and you'd piss off someone high-ranking, and oh god she's on her way back.

"Hi," you exclaim, and curse your nerves in spite of the drink. You just accept the bottle and drink because this is clearly already helping. "I want to talk more about your psychic thing. Can we do that?"

She smiles. Apparently there is such a thing as a troll smile, and it does something completely different to you, sets a totally different kind of nice nervousness swirling in your stomach.

"I'm starting to like humans," she says, and lounges back on the booth again. "What do you want to know?"

* * *

Two amazing weeks later, on the Tube to work the next day, Dirk has you completely pegged.

"You have a date, don't you? Business dinner, I mean," he says smoothly.

"Business dinner, yes," you say, all cheerfulness, and a pointed look. "Wow, for someone sooo resistant to say a word about their own _business dinners_ you're very interested in mine."

"I'm pretty sure you just undermined your own argument that it's a business dinner," Dirk says.

"I'm pretty sure you're being a very precious hypocrite." You mug at him. "We're going out for dinner. What are you implying?"

"Exactly what you implied. Only I'm going to outright state this is a bad idea." He clears his throat. "This is a bad idea."

"How is this a bad idea, tell me that," you prompt him. "We're just friendly and it can't possibly bleed into work."

"I'm talking about you." Dirk looks at you, directly at you, in his way. "You can't do a throwaway romance fling. You don't have the heart for it."

"Who said I was doing anything but flirting?" you whisper furiously. "I never said - "

"You like her. And you're drinking again. And she's a troll," he reminds you, like you hadn't noticed all of these things. "Trolls have a reputation when it comes to, um. Relationships with humans. It's biological."

"You're assuming a lot!" Yeah, you're a little upset now. "Fine! I've heard that about them too. I'll be careful."

He doesn't seem to be done with the topic yet. "Are you prepared to deal with this ending, because that's all I'm concerned about."

"You're pretty concerned about all this for something emotional," you half-tease him, mostly to shut him up.

"Jane said I should say something." He looks back at the book he'd carried as an excuse to ignore you before this conversation. "She worries about you."

"Uh-huh." You pop your gum. "Good to know you two are talking about me. Anyway! I'll manage. How did you know I was drinking?"

He looks at you frankly. "I've known since you came home from that first date."

You tense and blush and curse in every unladylike way inwardly, and busy yourself looking at your fingernails. "Dang! I chipped a nail."

"Priorities," Dirk says dryly.

"I got plans to get all decked out later, hon," you say, "and better this than that last thing." Well, some honesty isn't a bad thing.

"It'll work out," he says, in his even, calm tone.

"I just want something besides... I love you but I need something besides just work here. That's all you do, besides the telegrams - "

He raises a hand to stop you talking. Then he says nothing, carefully posed and still. You sigh heavily.

"Try to remember what I said," he finally says. "Even if you keep going."

You think you can manage that.

* * *

Dinner goes by fast, because despite the last few times you've spent time together, Terezi doesn't do much talking, and the two of you actually wind up eating during dinner. There's no talk about Alternia or her dream job for the Empire or favorite historical obsessions, there's no you talking about jazz and dancing and all the math babbling you can let out with enough hooch in your system. It's just talk about the weather, your dress, Terezi's gloves, the food… nothing, nothing really.

When you go to pay, she waves you off and pays, and you're so tensed that when you stand you nearly burst under the strain.

You could scream. _What did I do? Did I do anything? Is something wrong? Can I help? Tell me something! Tell me anything! I know I'm just some girl but tell me something, anything, I want to help you! Please, just say something, for God's sake!_

These are all the things you want to say, simultaneously, but you don't say any of them. You don't know her but you do but you don't, and even if you don't you want to and she's practically blockaded you. You just fight back frustrated tears for a split second, and make yourself smile when she finishes leaving the tip, for your own sake if not hers.

"Come with me," she says, and extends her hand.

You release a slow breath, and take her hand, the literal blind leading the metaphorically blind. You trust her.

* * *

Dirk was absolutely one hundred percent embarrassingly correct about you. You are so sappy right now, you're in Terezi Pyrope's flat, and she's pouring you a drink, and all you're thinking is how you need to leave before you get in over your head.

Because you're already in over your head. It's been two weeks and you're so flustered and upset over this beautiful troll woman who just "saw" you and felt right. It's romantic. You can't help that.

More than anything you want her to be okay. What does that even mean, what does that say about you?

"You all right?" you ask her, leaning onto the arm of the couch. She looks back at you, and you tilt your head at her. "You've been quiet."

Terezi stands still for a minute, her expression not changing, then she turns back away. Before you get to worry for more than a split second that you've offended her, she finally talks. "Made your drink. I'm quiet 'cos I saw something. Felt something? Something changed."

Oh, maybe this is worse than the other thing. You feel nauseous and you haven't even had more than wine with dinner yet. "At work?"

"Yeah, at work."

What are you supposed to say? "Um, I won't ask you about it. We can… we can talk about other things. I can try! To be distracting, I mean."

"That's what I wanted," Terezi says, and turns back around to offer the drink to you, head turned just slightly away from you. "To distract myself. You're distracting."

You're about to answer, not sure what exactly you're going to say, but she goes on. "Has your speccy friend talked to you already? Mine talked to me. Said I'm distracted."

"Distraction isn't the worst thing," you say, your voice a little small. This is heading in a direction, and you want it, but you don't? You don't know what you want.

"The worst thing is not being able to leave it there," she says, and gestures at your drink. You down some of it, happily, and she goes on. "The work, I mean. Leaving it there is good. Bringing it back with you - that's what I risk, Roxy, bringing it back with me because it's in my head."

"Is that why you talked to me that first day?" It clicks into place with you. Only then do you realize this is the first time she's called you by your first name. "Um. I mean, you wanted a distraction. To get out of your head. Because I'll talk to anyone, everyone knows that."

"Not on purpose." Terezi half-laughs, not unhappily, not happily either. "But that's what you've done. You've…. I don't know how these last two weeks, I, I start this, Roxy, I see everything. It's a gate. I open it and all the possibilities just… happen. And - "

"Some of them must be terrible," you say, then slap your hand over your mouth. You withdraw it instantly. "I'm. Is that what you were going to say?"

"Yes," she says; she's never sounded that uncertain in the short time you've known her. She's never sounded uncertain at all, really. "I wasn't going to say it but now that you mention it. Trolls see a lot of terrible things when we sleep. Ancestral memories. I didn't tell you that before, no one wants to hear that. But this is just as bad, but it's here, now, if we fuck up."

The language surprises you, but, war. People use that more now than ever, in the service especially. "I'm sorry," you say, softly.

She doesn't seem to know how to react to that. "Sometimes I think about leaving. I don't know that it would help, actually, and if I stay I might be able to help, not to mention that the ancestral memories are really terrible and these shouldn't be bothering me but they are, because these will happen to the people I care about, eventually, or affect them, and… it's inevitable, if we do nothing or the wrong thing."

"So we have to do something." You smile broadly. This is bittersweet. You can't do Enigma, you can't program something or write a formula to solve this problem, but you can do something. You can do this. "Like I said when you first talked to me. Allies. Remember?"

Terezi smiles, like it's a huge effort under the mental weight she's bearing, and you put your nearly-untouched drink aside. You go up close to her, though she goes all tense at you being close, and ask, "Can I…"

She nods. You hug her. She doesn't seem to know what to do for the first second, then a small shudder goes down her spine, and she wraps her arms around you. You smile against her shoulder and hold onto her.

"Americans don't usually solve problems with hugs, last I checked," she says.

"Brute force if necessary," you chirp, genuinely happily. "Is it necessary?"

"Maybe. I could go for some bloodsport," she teases you, and in the next breath adds, "troll thing."

Oh, that wicked tone of hers. You shouldn't like it, but you do. "I can try, but I'm no troll."

"Yeah, I know that."

The two of you are still really close. You look up into her face and smile up at her, unable to help it, just… you finally feel like you understand and you can do something besides math and tinkering, which you love doing but it's not nearly as rewarding as this. As her, right here.

She opens her mouth to say something else, but she closes it, so you take the chance to talk. "We can get sauced, orrrr we can talk about things, or - "

"You smell fantastic," she interrupts you, and you're just about to stutter out an answer in surprise when she kisses you.

"Mnf," you manage against her mouth, then you wrap an arm around her neck and return the kiss, faintly laughing when she pulls away.

"Something funny?" she murmurs.

"Not really." You're trying to remember Dirk and his warnings, but this is different. This isn't that. You're not being deceived or seduced. This feels way more right than that. "So… was that your contribution to what we should do tonight, or - "

"Oh," Terezi realizes, and is visibly startled into silence.

"It's okay," you assure her. "I'm teasing. Can we turn on the radio? I'm dying to dance."

She finds her voice when you say that. "I don't dance. I definitely don't dance."

"I don't roughhouse! You teach me, I'll teach you. But I go first." You take her hands, and pull her forward. "Come with me! I'll get the radio - sorry, wireless - do you think there's jazz on? God, I hope so - "

"Roxy," Terezi starts.

You turn back to her from a glance back to walk you both backwards. "What?"

She looks sheepish, an expression spectacularly out of place on her face. "Just don't tell anyone on Enigma."

"They wouldn't believe me anyway." You pull her forward slowly and run off to turn on the radio. "Hold onto your hat, Miss Pyrope, I'm gonna knock your socks off."

Terezi's smiling again, that smile, but it practically knocks you off of your feet. Dirk won't believe this. You're gonna get a troll codebreaker to bop like a pro.

You were meant for England. If this isn't proof, nothing is.


End file.
